The present invention relates to a method of guiding a missile towards a target according to the pre-characterising part of claim 1.
The present invention also relates to an arrangement in a missile for guiding the said missile towards a target according to the pre-characterising part of claim 4.
Several earlier methods of guiding a missile towards a target already exist. One method frequently encountered is so-called visual bearing guidance. Furthermore, there are methods of supplementing the visual bearing guidance with some function for enhancing the trajectory profile in the vertical plane for the purpose of obtaining increased performance. By means of this function the missile aims slightly higher than indicated by the line of sight, thereby producing a curvature of the missile trajectory.
U.S. Pat. No. 5,082,200 relates to a method of guiding a missile towards a point of interception with a target in the form, for example, of a satellite. A characteristic of the target, however, is that it has a known or predictable trajectory profile. The course of the missile is made to deviate from a collision course with the target by an angle dependent upon the distance to the target. The further the missile is from the target, the greater the angle of deviation.
This method is used for missiles propelled by solid fuel engines, in which the engines are fired at certain intervals and in which the engine constitutes the sole control element for guiding the missile.
One object of the present invention is to produce a method and an arrangement for guiding a missile towards a target that represent an improvement on the earlier known system described above.
The object has been achieved by means of a method for guiding a missile towards a target that has the characteristics specified in claim 1.
An arrangement for performing the said method has the characteristics specified in claim 4.
Preferred methods and embodiments also have any or some of the characteristics specified in the subordinate claim for each claim category.
The method and the arrangement according to the invention have various advantages:
The missile is guided towards a point above the target in order to make use of the lower air resistance at higher altitude, with a view to optimising the trajectory of the missile in respect of any chosen criterion, for example maximum final velocity or maximum average velocity, or for the lowest possible fuel consumption. The latter may be utilised, among other things, if the missile calculates that it cannot reach the target by flying a straight trajectory, since the missile can climb to an altitude at which the fuel consumption is lower and in this way increase the range. Alternatively the missile maintains that altitude in order, simply via an active homing device, to activate the target""s missile warning system for as long a time as possible.
The missile can be manoeuvred on to a trajectory such that the kinematic performance of the missile is improved compared to previously known methods.
As stated earlier, the method and the arrangement offer the freedom to select the optimisation criterion and final velocity conditions. In addition the trajectory of the missile can be adjusted as the scenario develops (interception point migration).
The method and arrangement according to the invention permit speculation on target behaviour, such speculation being used in estimating the point of interception. In this way the target behaviour and thus the point of interception can be estimated, for example from knowledge of the type of target.
An improved performance can be obtained in that the method and the arrangement can be used both in the trajectory phase of the missile and at least partially in its final phase.